Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is The Royal Society of Chemistry 2016 Supporting Information Branched polyethylenimine grafted electrospun polyacrylonitrile fiber membrane: A novel and effective adsorbent for Cr(VI) remediation in wastewater Rui Zhao, a Xiang Li,* a Bolun Sun, a Yanzi Li, a Yumei Li, a Rui Yang b and Ce Wang* a a Alan G. MacDiarmid Institute, Jilin University, Changchun 130012, PR China. b Changchun Monitoring Station,National UrbanWater-supply and Water Quality Monitoring Net,Changchun 130041,PR China. * Corresponding authors: Tel.: +86-431-85168292; Fax: +86-431-85168292. Email address: xiangli@jlu.edu.cn (X. Li), cwang@jlu.edu.cn (C. Wang). S-1
Preparation of electrospun b-pei/pva composite fibers (bpei/pva) and b-pei modified electrospun PAN fiber by hydrothermal route (bpei-pan(ht)) bpei/pva composite nanofibers were fabricated by electrospinning a 8 wt% bpei/pva (w/w = 0.32:1) mixture aqueous solution. The as-prepared electrospun fibers were placed inside a desiccator containing chemical cross-linking agent glutalraldehyde (GA, 50%) at 20 C for 18 h to conduct the cross-linking. The crosslinked fibers were then dried in vacuum oven at 60 C overnight. For bpei-pan(ht), 40 ml b-pei aqueous solution (20 mg/ml) and 60 mg electrospun PAN fibers were transferred into the Teflon-lined stainless steel autoclave (50.0 ml) and heated to 160 C for 24 h. After cooling down to room temperature, the as-prepared fiber membrane was washed several times with distilled water and ethanol, and then dried in vacuum oven at 60 C overnight. S-2
Fig. S1 The water flux for bpei-epan with the thickness of 150 m. The membrane filtration system is equilibrated with deionized water prior to the experiment and the Fig. S1 shows this process using the 150 m bpei-epan membrane as the representative. Fig. S2 SEM images of (a) EPANF, (b) bpei-epan-2, (c) bpei-epan-4, (d) bpei-epan-8, and (e) bpei-epan-12 at low magnification. S-3
Fig. S3 SEM images of b-pei grafted PAN synthetic fibers. As shown in Fig. S3, the diameter of b-pei grafted PAN synthetic fibers is more than ten micrometers, which is much higher than b-pei grafted electrospun PAN fibers. S-4
Fig. S4 TEM images of (a) EPANF, (b) bpei-epan-2, (c) bpei-epan-4, (d) bpei-epan-8, and (e) bpei-epan-12 (the bars are all 2 m). S-5
Table S1 Comparison of the maximum adsorption capacity (q m ) of Cr(VI) onto bpei- EPAN with other adsorbents. adsorbents q m initial T Ref (mg/g) ph ( C) amino functionalized GO decorated with Fe 3 O 4 nanoparticles 124.5 [1] polyethylenimine modified biochar 435.7 30 [2] polyethylenimine-functionalized PVA magnetic microspheres 88.4 [3] polyethylenimine modified ethyl cellulose 36.8 3.0 NR [4] polyvinylamine modified polyester fibers 26.2 3.0 20 [5] electrospun nanofibrous polyethylenimine mat 108.9 3.0 [6] magnetic nanoparticles functionalized by polyethyleneimine 159.0 [7] Flower-Like PA6@Mg(OH) 2 electrospun nanofibers 296.4 [8] Polyethylenimine modified poly(glycidyl methacrylate) microspheres 505.1 [9] b-pei grafted electrospun PAN fiber membrane 637.5 2.5 20 This work a NR, not reported. References 1 D. Zhao, X. Gao, C. Wu, R. Xie, S. Feng and C. Chen, Appl. Surf. Scie., 2016, 384, 1. 2 Y. Ma, W. J. Liu, N. Zhang, Y. S. Li, H. Jiang and G. P. Sheng, Bioresource Technol., 2014, 169, 403. 3 X. Sun, L. Yang, Q. Li, Z. Liu, T. Dong and H. Liu, Chem. Eng. J., 2015, 262, 101. 4 B. Qiu, J. Guo, X. Zhang, D. Sun, H. Gu, Q. Wang, H. Wang, X. Wang, X. Zhang, B. L. Weeks, Z. Guo and S. Wei,ACS Appl. Mater. Interfaces, 2014, 6, 19816. 5 T. Mayer-Gall, K. Opwis and J. S. Gutmann, J. Mater. Chem. A., 2015, 3, 386. 6 Y.Ma, B. Zhang, H. Ma, M. Yu, L. Li and J. Li, RSC Adv., 2016, 6, 30739 7 B. Chen, X. Zhao, Y. Liu, B. Xu and X. Pan, RSC Adv., 2015, 5, 1398. 8 B. B. Jia, J. N. Wang, J. Wu and C. J. Li, Chem. Eng. J., 2014, 4, 98. 9 X. Sun, L. Yang, H. Xing, J. Zhao, X. Li, Y. Huang and H. Liu, Colloids Surf., A: Physicochem. Eng.Aspects, 2014, 457, 160. S-6
Fig. S5 SEM images of bpei/pva (a), bpei-pan(ht) (b) and bpei-epan after ten adsorption-regeneration cycles (c). Fig. S6 Stress-strain curves of EPANF and bpei-epan. S-7
Table S2 Mechanical properties of EPANF and bpei-epan. sample tensile strength Elongation at break Young s modulus (MPa) (%) (MPa) EPANF 7.91±0.22 30.59±1.33 56.18±2.47 bpei-epan 20.97±1.70 20.43±0.96 455.05±3.02 Each measurement was repeated at least three times. Young s modulus was determined from the initial slope of the stress strain curves. Fig. S7 SEM images for cross-section part of the membrane (a) and the bpei-epan after ten filtration-regeneration cycles (b). S-8
Fig. S8 (a) The filtration cell; and (b) the Cr(VI) solution before and after filtration. Table S3 Filtration of the real water sample (initial Cr(VI) concentration: 0.208 mg/l) by bpei-epan filter membranes of different thickness. membranes thickness ( m) 50 100 150 0 concentrations in the filtrate (mg/l) 0.037 0.034 0.032 0.031 S-9
Fig. S9 Adsorption and desorption of Cr(VI) from aqueous solution through filtration. S-10